Whitesides Research

Techniques: Microfluidics

Droplet microfluidics for nucleation studies - Part II

Ice nucleation in a microfluidic chip, part 2

Metastable fluids, such as supercooled water, can be difficult to produce and maintain in a metastable state using large-scale containers. We produced supercooled water as cold as is possible: approximately -37 degrees Celsius in our system (further cooling is impossible due to the homogenous nucleation of ice).We used droplet microfluidics to produce special containers for supercooled water: water is contained in small droplets ~100 microns in diameter that are surrounded by a liquid container – a moving stream of liquid fluorocarbon.

This movie shows how drops of water freeze after the homogenous nucleation of ice. Such freezing is a two-stage process: (1) crystals of ice grow rapidly until the drop becomes a mixture of ice and water at a temperature of 0 degrees Celsius, then (2) the ice-water mixture freezes completely, at a slower pace, being cooled by the carrier fluid which has a temperature around -40 degrees Celsius.

Last updated on November 17, 2011

Droplet microfluidics for nucleation studies - Part I

Ice nucleation in a microfluidic chip, part 1

Metastable fluids, such as supercooled water, can be difficult to produce and maintain in a metastable state using large-scale containers. We produced supercooled water as cold as is possible: approximately -37 degrees Celsius in our system (further cooling is impossible due to the homogenous nucleation of ice). We used droplet microfluidics to produce special containers for supercooled water: water is contained in small droplets ~100 microns in diameter that are surrounded by a liquid container – a moving stream of liquid fluorocarbon.

This movie shows how we produce drops of supercooled water on a microfluidic chip, continuously cooling water from room temperature until it freezes due to homogeneous nucleation at temperatures close to -40 degrees Celsius

Last updated on November 17, 2011

Group Intranet | Harvard University Department of Chemistry and Chemical Biology
Site Designed and maintained by Richard Kwant | © 2011 Whitesides Research Group
This site is best viewed with IE8+, Firefox, Chrome, and Safari 5+